With the spiraling cost of land and new building construction, a need has arisen to expand existing building structures. In accordance with the present invention, it is possible to extend the roof of a building structure in order to obtain additional space. Thus, through the present invention, it is possible to take advantage of the existing structure and land use and increase the usable floor space to as much as double the original capacity. This expansion capability can be built into new structures for future expansion purposes of retrofiltered into existing structures requiring immediate expansion. The hydraulic lifting and telescopic column system of the present invention, affords the capability of expanding a building structure, at far less cost and time than is required to build a new separate or adjoining structure. Also, a commercial structure can be expanded with a minimum disruption to the normal working routine and additional working or storage space can be obtained very quickly. The present invention, in addition to being used for adding a story to a building, can also be used to increase the head space in a factory or warehouse. Thus, instead of placing a floor under the raised roof to essentially double the floor space, it is possible to leave out the floor and increase the head space in accordance with new needs requiring greater roof heights. Accordingly, the present invention affords an economic and logical approach to commercial expansion, while overcoming obstacles such as increasing expansion costs, zoning problems, construction bans, and disruption to personnel.